Batteries are electrochemical cells which store and supply electrical energy as a product of a chemical reaction. In their simplest conceptualization, batteries have two electrodes, one that supplies electrons by virtue of an oxidation process occurring at that electrode, termed the anode (hereinafter, “anodic processes”), and a second one that consumes electrons by virtue of a reduction process occurring at that electrode, termed the cathode (hereinafter, “cathodic processes”). Thin film ion batteries, including those of the thin film solid state lithium ion type, can be prepared from various deposition techniques to fabricate anode, cathode, and electrolyte materials bonded together to form the battery, individual cells of which may typically be less than about 25 microns in thickness. Such techniques may typically include depositing thin films of such materials using vacuum deposition or other techniques that result in similar thin films, to produce the “thin film” batteries. Thin film batteries are often employed in applications in which space and weight may preferably be conserved and extremely long cycle life may be desired.
Lithium anodes have presented issues in past lithium thin film battery techniques due to the high reactivity of lithium; however, a buried lithium anode was described in U.S. Pat. No. 6,805,999 (which has co-ownership and co-inventor overlap herewith), to provide stable thin film, solid state, lithium anode batteries. Note, U.S. Pat. No. 6,805,999 is incorporated herein by this reference as if fully set forth here for all that it teaches and suggests.
Moreover, the prior art has begun to address an additional desideratum of increasing thin film battery capacity and/or current delivery. In one track, it has been found desirable to increase the amount of lithium in a battery; however, it has been found that many materials used in thin film solid state applications cannot be structurally effective at larger sizes. For example, a good solid state electrolyte, lithium phosphorus oxynitride (also known as LiPON) is a brittle ceramic subject to cracking when subject to moderate expansion. A further alternative is in the provision of flexible materials for thin film electronic devices such as might include batteries. However, successful lithium ion, thin film, solid state battery techniques do not yet appear to have been successfully achieved in flexible forms.